drm/i915/dp_mst: Fix enabling pipe clock for all streams

commit afb2c4437dae ("drm/i915/ddi: Push pipe clock enabling to encoders")
inadvertently stopped enabling the pipe clock for any DP-MST stream
after the first one. It also rearranged the pipe clock enabling wrt.
initial MST payload allocation step (which may or may not be a
problem, but it's contrary to the spec.).

Fix things by making the above commit truly a non-functional change.

Fixes: afb2c4437dae ("drm/i915/ddi: Push pipe clock enabling to encoders")
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=107365
Reported-by: Lyude Paul <lyude@redhat.com>
Reported-by: dmummenschanz@web.de
Tested-by: dmummenschanz@web.de
Tested-by: Lyude Paul <lyude@redhat.com>
Cc: Lyude Paul <lyude@redhat.com>
Cc: dmummenschanz@web.de
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Lyude Paul <lyude@redhat.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180831174739.30387-1-imre.deak@intel.com
(cherry picked from commit 2b5cf4ef541f1b2facaca58cae5e8e0b5f19ad4c)
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>

drivers/gpu/drm/i915/intel_ddi.c

@@ -2708,7 +2708,8 @@ static void intel_ddi_pre_enable_dp(struct intel_encoder *encoder,
 	if (port != PORT_A || INTEL_GEN(dev_priv) >= 9)
 		intel_dp_stop_link_train(intel_dp);
 
-	intel_ddi_enable_pipe_clock(crtc_state);
+	if (!is_mst)
+		intel_ddi_enable_pipe_clock(crtc_state);
 }
 
 static void intel_ddi_pre_enable_hdmi(struct intel_encoder *encoder,
@@ -2810,14 +2811,14 @@ static void intel_ddi_post_disable_dp(struct intel_encoder *encoder,
 	bool is_mst = intel_crtc_has_type(old_crtc_state,
 					  INTEL_OUTPUT_DP_MST);
 
-	intel_ddi_disable_pipe_clock(old_crtc_state);
-
-	/*
-	 * Power down sink before disabling the port, otherwise we end
-	 * up getting interrupts from the sink on detecting link loss.
-	 */
-	if (!is_mst)
+	if (!is_mst) {
+		intel_ddi_disable_pipe_clock(old_crtc_state);
+		/*
+		 * Power down sink before disabling the port, otherwise we end
+		 * up getting interrupts from the sink on detecting link loss.
+		 */
 		intel_dp_sink_dpms(intel_dp, DRM_MODE_DPMS_OFF);
+	}
 
 	intel_disable_ddi_buf(encoder);
 

drivers/gpu/drm/i915/intel_dp_mst.c

@@ -166,6 +166,8 @@ static void intel_mst_post_disable_dp(struct intel_encoder *encoder,
 	struct intel_connector *connector =
 		to_intel_connector(old_conn_state->connector);
 
+	intel_ddi_disable_pipe_clock(old_crtc_state);
+
 	/* this can fail */
 	drm_dp_check_act_status(&intel_dp->mst_mgr);
 	/* and this can also fail */
@@ -252,6 +254,8 @@ static void intel_mst_pre_enable_dp(struct intel_encoder *encoder,
 	I915_WRITE(DP_TP_STATUS(port), temp);
 
 	ret = drm_dp_update_payload_part1(&intel_dp->mst_mgr);
+
+	intel_ddi_enable_pipe_clock(pipe_config);
 }
 
 static void intel_mst_enable_dp(struct intel_encoder *encoder,